A special composition for a special election.
The states do not simply send the same people as to the Bundesrat. Their parliaments elect Federal Convention members under the relevant rules. These may include people without a parliamentary mandate.
The Federal Convention does not operate as a permanent legislative parliament. Its task is to elect the head of state. Its name should therefore be learned as a separate institutional term.

The other three answers
The shared prefix “Bundes-” does not identify the right institution.
the Bundesrat
The Bundesrat contains state government members. It is not the special convention that elects the President.
the federal parliament
Bundestag MPs are only one part of the Federal Convention. The Bundestag alone does not elect the head of state.
the Federal Constitutional Court
The Federal Constitutional Court decides constitutional questions. It does not elect the Federal President.
The electoral procedure can involve several ballots.
The first two ballots require a majority of Federal Convention members. A further ballot is decided by the highest number of votes. These rules should not be confused with the Chancellor election.
The term is five years, and one consecutive re-election is permitted. This explains why a person may appear more than once on presidential election pages without holding an unlimited appointment.
Article 54 · Basic Law ↗Federal Convention → Federal President.
Bundestag → Federal Chancellor is the other election pair.
Three words for this question
- die BundesversammlungFederal Convention
- The special body that elects the Federal President.
- die Amtszeitterm of office
- The prescribed period for holding an office.
- die Landesvertretungstate parliament
- Here, the elected representative assembly of a federal state.
